Số tiền Nam mua sách: \(320000\times\dfrac{1}{4}=80000\) (đồng)

Số tiền Nam mua vở: \(90000:\dfrac{2}{3}=135000\) (đồng)

Số tiền Nam mua dụng cụ học tập: \(320000-\left(80000+135000\right)=105000\) (đồng)

Giúp mình đi các bạn 🥺

`B=(2015+2016+2017)/(2016+2017+2018)`

`=2015/(2016+2017+2018)+2016/(2016+2017+2018)+2017/(2016+2017+2018)`

Vì `2015/(2016+2017+2018)<2015/2016`

`2016/(2016+2017+2018)<2016/2017`

`2017/(2016+2017+2018)<2017/2018`

`=>B<A`

Bài 5

B= \(\dfrac{2015}{2016+2017+2018}\)+\(\dfrac{2016}{2016+2017+2018}\)+\(\dfrac{2017}{2016+2017+2018}\)

Ta có:\(\dfrac{2015}{2016}\)>\(\dfrac{2015}{2016+2017+2018}\),\(\dfrac{2016}{2017}\)>\(\dfrac{2016}{2016+2017+2018}\),\(\dfrac{2017}{2018}\)>\(\dfrac{2017}{2016+2017+2018}\)

⇒A>B

Giải:

Ta có:

\(B=\dfrac{2015+2016+2017}{2016+2017+2018}\) 

\(B=\dfrac{2015}{2016+2017+2018}+\dfrac{2016}{2016+2017+2018}+\dfrac{2017}{2016+2017+2018}\) 

Vì \(\dfrac{2015}{2016}>\dfrac{2015}{2016+2017+2018}\) 

\(\dfrac{2016}{2017}>\dfrac{2016}{2016+2017+2018}\) 

\(\dfrac{2017}{2018}>\dfrac{2017}{2016+2017+2018}\) 

\(\Rightarrow A>B\) 

Chúc bạn học tốt!

a,\(\dfrac{2}{3}\)-\(\dfrac{5}{7}\).\(\dfrac{14}{25}\)

=\(\dfrac{2}{3}\)-\(\dfrac{2}{5}\)

=\(\dfrac{4}{15}\)

b,\(\dfrac{-2}{5}\).\(\dfrac{5}{8}\)+\(\dfrac{5}{8}\).\(\dfrac{3}{5}\)

=\(\dfrac{5}{8}\).(\(\dfrac{-2}{5}\)+\(\dfrac{3}{5}\))

=\(\dfrac{5}{8}\).\(\dfrac{1}{5}\)

=\(\dfrac{1}{8}\)

Giải:

a) \(\dfrac{2}{3}-\dfrac{5}{7}.\dfrac{14}{25}=\dfrac{2}{3}-\dfrac{2}{5}=\dfrac{4}{15}\) 

b) \(\dfrac{-2}{5}.\dfrac{5}{8}+\dfrac{5}{8}.\dfrac{3}{5}\) 

\(=\dfrac{5}{8}.\left(\dfrac{-2}{5}+\dfrac{3}{5}\right)\) 

\(=\dfrac{5}{8}.\dfrac{1}{5}\) 

\(=\dfrac{1}{8}\) 

c) \(\left(\dfrac{1}{2}\right)^2-1\dfrac{1}{2}+0,5.\dfrac{12}{5}+5\%\) 

\(=\dfrac{1}{4}-\dfrac{3}{2}+\dfrac{1}{2}.\dfrac{12}{5}+\dfrac{1}{20}\) 

\(=\dfrac{-5}{4}+\dfrac{6}{5}+\dfrac{1}{20}\) 

\(=0\) 

Chúc bạn học tốt!

c,\(\left(\dfrac{1}{2}\right)^2\)-1\(\dfrac{1}{2}\)+0,5.\(\dfrac{12}{5}\)+5%

=\(\dfrac{1}{4}\)-\(\dfrac{3}{2}\)+\(\dfrac{1}{2}\).\(\dfrac{12}{5}\)+\(\dfrac{1}{20}\)

=\(\dfrac{1}{4}\)-\(\dfrac{3}{2}\)+\(\dfrac{6}{5}\)+\(\dfrac{1}{20}\)

=\(\dfrac{-5}{4}\)+\(\dfrac{6}{5}\)+\(\dfrac{1}{20}\)

=\(\dfrac{-1}{20}\)+\(\dfrac{1}{20}\)

=0

=

1.the souvenirs inside the temple of literature are sold at a higher price

2. can you help me to make a glass of lemonade, please?

3.Linh finds playing chess interesting because he can play it with his close friend.

4.i think people in the countryside eat a lot of fresh vegetable so they live longer

5.volunteer work is very hard for my sister but she she really enjoys doing it

1 doesn't like

2 was reconstructed

3 have ever tried

4 will you take

5 is made

6 often rains - isn't raining

7 had

8 are standing

9 are

1. doesn't like

2. was reconstructed

3. I have ever tried

4. will you take

5. is made

6. often rains - isn't raining

7. had

8. are standing

9. are

a) Ta có: 3x-17=x+3

\(\Leftrightarrow3x-x=3+17\)

\(\Leftrightarrow2x=20\)

hay x=10

b) Ta có: \( \left|x-3\right|-12=\left|-5\right|\)

\(\Leftrightarrow\left|x-3\right|=17\)

\(\Leftrightarrow\left[{}\begin{matrix}x-3=17\\x-3=-17\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=20\\x=-14\end{matrix}\right.\)

Vậy: \(x\in\left\{20;-14\right\}\)

c) Ta có: \(25-\left(x-5\right)=-415-\left(15-415\right)\)

\(\Leftrightarrow25-x+5=-415-15+415\)

\(\Leftrightarrow30-x=-15\)

hay x=45

Vậy: x=45

3x - 17 = x + 3 

3x = x+3 +17 

3x = x+20

3x-x=20

2x = 20

x= 20:2

x = 10

b ) |x-3| -12 = |-5|

|x-3| = 12 + 5

|x-3|=17

\(\left[{}\begin{matrix}x-3=17\\x-3=-17\end{matrix}\right.\)   =>\(\left[{}\begin{matrix}x=17-3\\x=-17-3\end{matrix}\right.\)=>\(\left[{}\begin{matrix}x=14\\x=-20\end{matrix}\right.\)  

vậy x= 14 hoặc x= -20

c) 25 -(x-5) = -415 -(15-145)

25-(x-5) = 15

x-5 = 25 -15

x-5 = 10

x = 10 - 5

x = 5

1. How will they travel to HN?

2. Where is the high school?

3. Who would you like to take the trip with?

4. Does she like visiting famous historical places?

5. How long has your brother learnt to play the guitar?

6. Why do you often listen to English songs?

7. How far is it from Hue to HCM City?

1. How will they travel to Ha Noi?

2. Where is the high school?

3. Who would you like to take the trip with?

4. Does she like visiting famous historical places?

5. How long has your brother learnt to play the guitar?

6. Why do you often listen to English songs?

7. How far is it from Hue to HCM City?

1. How will they travel to HN?

2. Where is the high school?

3. Who would you like to take the trip with?

4. Does she like visiting famous historical places?

5. How long has your brother learnt to play the guitar?

6. Why do you often listen to English songs?

7. How far is it from Hue to HCM City?

câu 12 :A

câu 13 :B

câu 14 :D

câu 15 :A

câu 16 :D

câu 17 :A

câu 18 :C

câu cuối mik chx chắc lắm